Chapter 8 Tutorial

Measurement Fundamentals

The 4-wire ohms method is used in systems where lead resistances can become quite large and variable and in automated test applications where cable lengths can be quite long. The 4-wire ohms method has the obvious disadvantage of requiring twice as many switches and twice as many wires as the 2-wire method. The 4-wire ohms method is used almost exclusively for measuring lower resistance values in any application, especially for values less than 10Ω and for high-accuracy requirements such as RTD temperature transducers.

HI-Source

HI-Sense

Itest

R =

Vmeter

 

 

Vmeter

 

 

 

Itest

 

 

 

 

 

 

 

 

LO-Sense

LO-Source

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